Constricted hysteresis loops of unpolarized polycrystalline barium titanate normal and differential permittivities

A QUANTITATIVE investigation was made of the change in normal and differential permittivities with field strength and with time in unpolarized ceramic barium titanate disks at 25 C (degrees centigrade) as manifested in the deconstriction of 60-cps (cycles-per-second) hysteresis loops. Empirical expressions, which are first approximations giving the variation of the permittivity with field strength at stated time after start, were deduced for both branches of each permittivity loop. At constant field strength, the normal permittivity εn varies as t^β where t is time and β is a constant.